[Computed tomography of the soft tissues of the neck. Lymph node metastases and their differential diagnosis. I. Methods and the principal CT criteria for lymph node metastases].

Standardisation of the examination method is imperative to guarantee reproducible and valid assessability of the cervical lymph node status. To this end, update high-resolution CT equipment of the third generation will be suitable, provided it meets certain minimum requirements, such as: 120 kV, 280 mAs, 480 projections over 360 degrees, 4-5 mm slice thickness, continuous tomography. If a primary tumour is known to exist, no plain examination is needed. The decisive examination is effected after intravenous administration of contrast medium in a dosage of 2.0-2.5 ml contrast medium/kg body weight (assuming a body weight of 70 kg, this would amount to 150 ml = 45 g iodine), one-third of the total dosage to be given as bolus and two-thirds as a rapid infusion. This procedure ensures sharp definition of lymph nodes against vessels and musculature over the entire period of examination. If tumour anamnesis has been established the size of the lymph node is significant for assessing the lymph node status. Even lymph node metastases less than 15 mm can be properly identified if the structure of the lymph nodes is known and employed as a criterion (central hypodensity with rim enhancement, inhomogeneity).